The contamination of water by oil, grease, fuel and combinations thereof is a significant problem in the U.S. Throughout the country there are establishments such as service stations, automatic repair shops, car washes, pressure cleaning of heavy construction equipment shops and a host of other types of establishments that generate contaminated water as a result of their cleaning processes. The contamination of water sewage systems and street drainage systems due to the careless and/or irresponsible discharge of contaminated waters is a major concern of the Environmental Protection Agency, state and local environmental agencies.
Management should keep the following facts in mind when dealing with possible petroleum contamination of ground or water.
It is illegal to discharge oil, grease or fuel into U.S. waterways and ground water.
The unacceptable amount is--any amount which produces a sheen on the water surface.
Waste oil presently under consideration and considered likely to be added to the "Hazardous Waste List."
Discharging oil waste to the ground has caused ground water contamination, resulting in contamination of local wells and water supplies, resulting in law suits, fines and cease operation orders.
Companies have been fined to the point of bankruptcy.
The "corporate veil" does not relieve corporate officers from personal liability suits when willful negligence is involved.
When oil, grease or fuel contamination of waste water exceeds permissible levels, the contaminants must be removed before discharge is safe and legal. There are numerous known methods of removing oil, grease and fuel available on the open market. However, they all possess disadvantages which exceed their advantages. Below are listed several known systems and showing of the advantages and disadvantages of each.
GRAVITY--Relies on the ability of oil to float to the water surface and is then skimmed off.
Advantages: Inexpensive, easy to use, no moving parts. PA0 Disadvantages: PA0 Advantages: PA0 Disadvantages: PA0 Advantages: PA0 Disadvantages: PA0 Advantages: PA0 Disadvantages: PA0 Advantages: PA0 Disadvantages: PA0 Advantages: PA0 Disadvantages: PA0 Advantages: PA0 Disadvantages:
Requires frequent attention PA1 Will not work under pressure or heavy flow PA1 Will not remove light or emulsified oil PA1 Poor efficiency levels above 100 ppm PA1 Easy to operate PA1 No moving parts PA1 Units are smaller than gravity systems PA1 Requires frequent attention PA1 Poor efficiency levels above 50 ppm PA1 Will not work under pressure or heavy flow PA1 Will not remove light or emulsified oil PA1 Simple to use PA1 Inexpensive PA1 Requires an electric motor PA1 Will not work under pressure or heavy flow PA1 Will not remove light or mechanically emulsified oil PA1 Poor efficiency PA1 Requires electricity PA1 Small in size PA1 Will work under pressure PA1 Very poor efficiency levels above 100 ppm PA1 Very difficult to clean PA1 Will not remove light or emulsified oil PA1 Will not work in heavy flows PA1 Good efficiency levels below 10 ppm PA1 Will work under pressure PA1 Will work on light and emulsified oil PA1 Requires daily servicing by trained technicians PA1 Units are expensive PA1 Operates on a batch system, not a continuous flow PA1 Requires electricity PA1 Excellent efficiency below 10 ppm PA1 Will work on emulsified oils PA1 Will work under pressure PA1 Possible side effects of bacteria problem PA1 Requires a trained technician to operate PA1 Expensive to operate PA1 Requires electricity PA1 Excellent efficiency less than 10 ppm PA1 Will work under pressure PA1 Will work on light or emulsified oil PA1 Very expensive to operate and purchase initially PA1 Large in size PA1 Operates on a batch system, not a continuous flow PA1 Requires electricity
COALESCING/GRAVITY--Relies on the ability of oil to float to the water surface. The coalescing function works on the principle that oil is attracted to teflon or polypropylene. Small oil particles attach to the teflon or polypropylene and form oil globules which break away and rise to the surface faster for skimming.
METALLIC ATTRACTION--This system is generally made up of a metal belt which runs through the oily water. The free oil is attracted to the metal belt which rotates out of the water. The oil is then scraped off by a scraper blade and drained into a slop tank.
POLYPROPYLENE ATTRACTION--This is a simple method which uses the oil attracting properties of polypropylene. A series of polypropylene fins and baffles are placed in the waste water flow. The heavy oils are attracted to the polypropylene, which can be removed and cleaned.
CHEMICAL TREATMENT--This system treats the waste-water with coagulation, flocculation and polymers and alum which promotes the oil to settle or float in a floc, making removal easier.
BACTERIA TREATMENT--A new technology that uses bacteria to alter the composition of oil.
ULTRAFILTRATION--Uses ultrafine membranes to filter out oil and contaminants.
CENTRIFUGAL--Uses centrifugal force to separate liquids and solids of different specific gravity.
As can be seen from the above tabulation, there are many known systems, each having their own advantages and disadvantages with no one system possessing all the advantages of the instant invention as will be set forth hereinafter.